Man the slave & master / by Mark Graubard.

  • Graubard, Mark, 1904-1992.
Date:
1939
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Man the slave & master / by Mark Graubard. Source: Wellcome Collection.

    89/388 (page 73)
    contains chemical substances which act as buffers. They absorb all excess acid or alkali and maintain a constant level of acidity, actions which are of the utmost signifi cance since without them life as we know it could not continue. Chemical buffers act as shock absorbers because of their unique composition. Their peculiar properties permit them to maintain constant acidity even outside the body, in agreement with well-known and simple laws. Besides utilizing these ordinary chemical buffers, the body is also equipped with elaborate mechanisms which may be called physiological buffers. We may cite a few illustrations. The nervous system possesses a respiratory centre consisting of nerves controlling the muscles con cerned in breathing. When the blood has an excess of alkali this centre is stimulated and reduces ventilation. Much of the carbon dioxide normally ejected by the lungs in exchange for oxygen is then retained in the blood, which in consequence becomes acid. The excess alkalinity is thus neutralized. When, on the other hand, blood contains an excess of acid the respiratory centre is stimulated and breathing is increased. More carbon dioxide is then eliminated, thus diminishing acidity. Here we deal with a complex organic adjustment which acts as a buffer and maintains original conditions in the face of disturbances. The kidney, a gland through which the animal's blood is filtered, is another organ of great significance in main taining internal constancy. The kidney removes from the blood many substances which accumulate as waste pro ducts of cellular activity. Its main function, broadly speak ing, is the preservation of normal composition in the blood. It maintains definite concentration levels of all constitu ents by removing excess and withholding substances whose quantity may, for a brief period, fall below normal. The constancy of the internal environment and the capacity of a living organism to make adjustments and